Left ventricular cardiac assist devices made of a polyurethane polymer have been developed and tested in vivo in calves and humans. A major potential problem, however, impeding the long-term usage of such artificial devices, is calcification of the neointimal surface, severely altering the compliancy of the pump. The overall objective of this project is to define the mechanism of calcification and understand the events leading to the pathological deposition of calcium in cardiac assist devices. Specifically, the implants will be studied by morphological and biochemical methods to determine if: (1) specialized cells (perhaps osteogenic) and organelles (matrix vesicles) or other aspects of cell metabolism such as effects of local pH changes, lysosomal activity, and cell death are present which might facilitate mineralization; (2) phosphoproteins or gamma-carboxyglutamic acid calcium binding proteins are present, similar to those occurring in the organic matrix of normal hard tissue. The time course of calcification, with particular notice to the earliest deposition of mineral, will be evaluated by electron microscopy, tetracycline labelling and with specialized histological techniques for the detection of calcified areas. Transmission and scanning microscopy, electron diffraction, X-ray calcium probe analysis, specific enzyme analysis (acid and alkaline phosphatase), amino acid content and calcium binding measurements, will be performed on all samples. In addition, to determine if de novo synthesis of calcium binding proteins occurs in the bladder, tissue culture techniques will be utilized. Identification of the calcium binding proteins will be determined by amino acid content, immunological techniques, electrophoretic identity with protein standards and peptide mapping. As a result of the proposed research concerning the determinants of mineralization, appropriate chemical, cellular or possible inclusion of time-release pharmacologic agents for modification of the synthetic bladder pumps could be considered to reduce mineralization.